In the H90 Control app:

• Select the Parameters tab at the bottom.
• Up top, right-click on the 3 dots, just to the left of A or B Preset.
• Select Import H9 ‘h9z’ Preset …

The same process above applies in the Preset Library tab (along the bottom).

Or go to the extreme bottom left icons in any tab, and locate the Import List icon (the 3rd / middle one of 5 icons).

• Right-click on it, and select Import H9 List …

There is also drag ‘n’ drop from a File Manager window on your computer, but I have never used that myself.  I like a little more control over what goes where.